Receiver-initiated multiple access for ad-hoc networks (RIMA)

Abstract

Receiver-initiated collision avoidance methods for use in ad-hoc wireless networks in which carrier sensing is available. A number of protocol variants are described including RIMA-SP (simple polling), RIMA-DP (dual-purpose polling), and RIMA-BP (broadcast polling). These handshake methods according to the invention are capable of correctly avoiding collisions within a network that contains hidden nodes, and the RIMA-DP protocol provides higher performance levels than attainable with existing handshaking protocols within the ad-hoc wireless networks. The use of dual-purpose polling allows a control packet to be sent which has alternative functions, such as requesting data from the polled node, if available, and if not available then providing a transmission request from the polling node to send data to the polled node.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. provisional application Ser. No. 60 / 225,019 filed on Aug. 11, 2000, incorporated herein by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]This invention was made with Government support under Grant No. F30602-97-2-0338, awarded by the Air Force Office of Scientific Research (AFOSR). The Government has certain rights in this invention.REFERENCE TO A COMPUTER PROGRAM APPENDIX[0003]Not ApplicableBACKGROUND OF THE INVENTION[0004]1. Field of the Invention[0005]The invention pertains generally to wireless ad-hoc networking, and more particularly to a medium access control protocol that provides correct collision-avoidance in wireless networks in which hidden terminals may exist.[0006]2. Description of the Background Art[0007]As the use of wireless systems become increasingly important, attention is being focused on a variety of wireless network protocols. A large body of...

AI Technical Summary

Benefits of technology

[0010]A method of handshaking between nodes within a medium access control protocol is described utilizing dual purpose polling that overcomes the packet collision problems within existing receiver-initiated protocols on networks in which one or more hidden terminals exist. The protocol methods of the present invention allow the collision-avoidance dialogues to be recast for control by senders, receivers, or both. Utilization of the resulting receiver-initiated collision-avoidance methods provide increased efficiency over sender-initiated collision-avoidance. Also incorporated within this description are analytical proofs to verify that correct collision-avoidance in networks subject to hidden terminals can be obtained using the collision-avoidance methods of the present invention.

[0014]A further aspect of the invention provides a broadcast polling mode, referred to as RIMA-BP (broadcast polling) wherein the ready-to-receive signals are communicated to a number of neighbors. Collision avoidance between multiple responses is facilitated by having the polled node send a ready-to-send (RTS) control packet to precede the sending of the data packet, wherein a polling node subject to multiple RTS control packets can send a no-transmission-request (NTR) control packet to prevent data packet collisions.

[0015]The conclusion from an analysis of the existing protocols, and the RIMA protocols of the present invention indicate that the use of receiver-initiated multiple access with dual-use polling (RIMA-DP) according to an aspect of the present invention provides the highest level of efficiency of the MAC protocols for single-channel networks utilizing asynchronous transmissions.

[0016]An object of the invention is to reduce the control overhead within single channel wireless networks.

[0017]Another object of the invention is to prevent packet collisions within wireless networks.

[0018]Another object of the invention is to provide a method in which both sender-initiated protocols and receiver-initiated protocols may be utilized for reducing the amount of necessary control traffic.

Problems solved by technology

A number of problems have been identified with existing and proposed wireless protocols.

One problems is the hidden-terminal problem of carrier sensing which reduces the performance of the carrier-sense multiple access (CSMA) protocol to that of the pure ALOHA protocol when the senders of packets are unable to hear one another, wherein the vulnerability period of packets extends to twice a packet length.

However, the MACA-BI protocol when utilized in a wireless network is unable to prevent data packet collisions within networks containing hidden terminals.

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